EPICS StreamDevice

https://paulscherrerinstitute.github.io/StreamDevice
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EPICS StreamDevice is a generic EPICS device support for devices with a byte stream-based...
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### Example Protocol File

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

This example demonstrates the basic structure of a Stream Device protocol file, including defining terminators, commands with input/output specifications, and initialization routines.

```protocol
# This is an example protocol file

Terminator = CR LF;

# Frequency is a float
# use ai and ao records

getFrequency {
    out "FREQ?"; in "%f";
}

setFrequency {
    out "FREQ %f";
    @init { getFrequency; }
}

# Switch is an enum, either OFF or ON
# use bi and bo records

getSwitch {
    out "SW?"; in "SW %{OFF|ON}";
}

setSwitch {
    out "SW %{OFF|ON}";
    @init { getSwitch; }
}

# Connect a stringout record to this to get
# a generic command interface.
# After processing finishes, the record contains the reply.

debug {
    ExtraInput = Ignore;
    out "%s"; in "%39c"
}


```

--------------------------------

### Protocol Example with Arguments

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

This example demonstrates how to define and use a protocol with arguments for output operations. The argument is used in the output string formatting.

```text
moveaxis {
 out "move$1 %.6f";
}
field (OUT, "@motor.proto moveaxis(X) motor1")
```

--------------------------------

### Protocol Definition for Example Record

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

The 'read' protocol definition corresponding to the 'ai' record example, showing how arguments are parsed and used.

```streamdevice
read { out 0x8$1 "READ $2"; in "%f,%(\$3recY\$1)f" }
```

--------------------------------

### Protocol Example with Input Arguments

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

This example shows how to use arguments in a protocol for input operations. The argument is passed to the protocol and used in the input command and format string.

```text
readpressure {
 out 0x02 0x00 $1;
 in 0x82 0x00 $1 "%2r";
}
field (INP, "@vacuumgauge.proto readpressure(0x84) gauge3")
```

--------------------------------

### StreamDevice Protocol for Getting ROI Start Value

Source: https://paulscherrerinstitute.github.io/StreamDevice/processing.html

Defines the StreamDevice protocol for the 'getROIstart' function. It sends a request 'ROI?' to the device and expects a reply starting with 'ROI ' followed by two floating-point numbers, capturing the first one.

```StreamDevice Protocol
getROIstart {
    out "ROI?";
    in  "ROI %f %*f";
}
```

--------------------------------

### Format String Parsing Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Illustrates how the 'source' pointer is advanced after parsing a format string, showing the state before and after the parse() call.

```text
 source       source
 before       after
 parse()      parse()
     |
"%39[0-9a-zA-Z]constant text"
    |
 conversion
 character
```

--------------------------------

### Configure VXI11 (GPIB over TCP/IP) for StreamDevice

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Example startup script configuration for a VXI11 device. Sets the StreamDevice protocol path and configures the VXI11 connection with IP address, host, and device parameters.

```shell
epicsEnvSet ("STREAM_PROTOCOL_PATH", ".:../protocols")

vxi11Configure ("PS1","192.168.164.10",1,1000,"hpib")

```

--------------------------------

### Configure TCP/IP Port for StreamDevice

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Example startup script configuration for a TCP/IP connection. Sets the StreamDevice protocol path and configures the asyn IP port with a specified address and port.

```shell
epicsEnvSet ("STREAM_PROTOCOL_PATH", ".:../protocols")

drvAsynIPPortConfigure ("PS1", "192.168.164.10:23")

```

--------------------------------

### Configure Serial Port for StreamDevice

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Example startup script configuration for a serial device. Sets the StreamDevice protocol path and configures the asyn serial port with specific options.

```shell
epicsEnvSet ("STREAM_PROTOCOL_PATH", ".:../protocols")

drvAsynSerialPortConfigure ("PS1","/dev/ttyS1")
asynSetOption ("PS1", 0, "baud", "9600")
asynSetOption ("PS1", 0, "bits", "8")
asynSetOption ("PS1", 0, "parity", "none")
asynSetOption ("PS1", 0, "stop", "1")
asynSetOption ("PS1", 0, "clocal", "Y")
asynSetOption ("PS1", 0, "crtscts", "N")

```

--------------------------------

### StreamDevice Record with Protocol Arguments

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

An example of an 'ai' record using the 'stream' DTYP, demonstrating complex protocol argument passing including macros and special characters.

```epics
record(ai, "$(PREFIX)recX5") {
    field(DTYP, "stream")
    field(INP,  "@$(PROTOCOLFILE) read(5, X\,Y $(PREFIX)) $(PORT)")
}
record(ai, "$(PREFIX)recY5") {}
```

--------------------------------

### String Concatenation Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Illustrates how a single string can be constructed from multiple quoted literals and byte values, separated by whitespace or commas.

```StreamDevice Protocol
"Hello world\r\n"
```

```StreamDevice Protocol
'Hello',0x20,"world",CR,LF
```

--------------------------------

### scalcout Record CALC Expression Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/scalcout.html

Example of a minimal valid CALC expression for scalcout records, ensuring OVAL is calculated.

```text
"0"
```

--------------------------------

### Configure ASYN Driver Path

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Adds the path to the asynDriver installation to the `configure/RELEASE` file. This enables StreamDevice to communicate with hardware via the asynDriver.

```makefile
ASYN=/home/epics/asyn4-45
```

--------------------------------

### Example of @init Exception Handler

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

This snippet shows how to use the @init exception handler to initialize an output record by reading a value from the device. It is called when an exception occurs, allowing for a clean reset or initialization.

```streamdevice
setPosition {
    out "POS %f";
    @init { out "POS?"; in "POS %f"; }
}    

```

--------------------------------

### AI Record Configuration for ROI Start

Source: https://paulscherrerinstitute.github.io/StreamDevice/processing.html

Configures an AI record to process the start value of a Region of Interest (ROI) from a device. It uses a StreamDevice input process file and specifies the device to communicate with.

```EPICS
record (ai "ROI:start") {
    field (DTYP, "stream")
    field (INP,  "@myDev.proto getROIstart dev1")
}
```

--------------------------------

### Configure EPICS_BASE Path

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Specifies the installation location of the EPICS base directory in the `configure/RELEASE` file. This is essential for the build process.

```makefile
EPICS_BASE=/home/epics/base-7.0.9
```

--------------------------------

### Handle Multi-line Messages

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use multiple 'in' commands for each line of input when a device sends multi-line messages. This example shows how to read a two-line message.

```Device Support
read_value {
in "Here is the value:";
in "%f";
}
```

--------------------------------

### Example Protocol Definition for Power Supply

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Defines 'getCurent' and 'setCurrent' protocols for a power supply device. The 'setCurrent' protocol includes an '@init' handler to call 'getCurent' during initialization. Assumes CR LF terminator.

```proto
Terminator = CR LF;

getCurent {
        out "CURRENT?";
        in "CURRENT %f A";
    }

setCurrent {
    out "CURRENT %.2f";
    @init {
        getCurent;
    }

}

```

--------------------------------

### Configure CALC Module Path

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Specifies the installation path for the EPICS calc module in the `configure/RELEASE` file. This is required if StreamDevice needs support for the sCalcout record.

```makefile
CALC=/home/epics/synApps/calc-R3-7-5
```

--------------------------------

### StreamDevice Protocol for Getting ROI End Value

Source: https://paulscherrerinstitute.github.io/StreamDevice/processing.html

Defines the StreamDevice protocol for the 'getROIend' function. It expects a reply starting with 'ROI ' and captures the second floating-point number, ignoring the first one using '%*f'. This protocol is designed to work with I/O Intr mode.

```StreamDevice Protocol
getROIend {
    in  "ROI %*f %f";
}
```

--------------------------------

### Get Client Name

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Retrieves the name of the client instance associated with this bus interface. Useful for logging and error messages.

```cpp
const char* clientName();
```

--------------------------------

### aao Record STRING Input Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Inputs array elements as strings when FTVL is STRING. Each input string is assigned to an array element.

```text
_Input:_ `VAL[i]=_x[i]_`
```

--------------------------------

### aao Record STRING Output Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Outputs array elements as strings when FTVL is STRING. Each element is treated as a separate string.

```text
_Output:_ `_x[i]_=VAL[i]`
```

--------------------------------

### Accessing scalcout Record Fields

Source: https://paulscherrerinstitute.github.io/StreamDevice/scalcout.html

Example of accessing fields A-L and AA-LL directly in scalcout records using format specifiers.

```text
"%(A)f"
```

```text
"%(BB)s"
```

--------------------------------

### LONG Converter Registration Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

This C++ code demonstrates how to define and register a custom converter class for handling long integers with the conversion character '%Q'. It shows the necessary includes, class definition with parse, printLong, and scanLong methods, and the RegisterConverter call.

```cpp
#include "StreamFormatConverter.h"

class MyConverter : public StreamFormatConverter
{
    int parse(const StreamFormat&, StreamBuffer&, const char*&, bool);
    bool printLong(const StreamFormat&, StreamBuffer&, long);
    ssize_t scanLong(const StreamFormat&, const char*, long&);
};

RegisterConverter(MyConverter,"Q");

// ... (implementation)

```

--------------------------------

### aao Record DOUBLE Input Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Inputs array elements as doubles, converting from the specified FTVL. FTVL must be FLOAT or DOUBLE.

```text
_Input:_ `VAL[i]=FTVL(_x[i]_)`
```

--------------------------------

### aao Record CHAR/UCHAR Output Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Outputs the complete aao as a single string of size NORD when FTVL is CHAR or UCHAR. The first NORD characters are printed.

```text
_Output:_ `_x_=range(VAL,0,NORD)`
```

--------------------------------

### Get Output Terminator

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Retrieves any terminator bytes that have been added to the output by the client.

```cpp
const char* getOutTerminator(size_t& length);
```

--------------------------------

### Get Lock Priority

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Returns the priority of the bus interface for lock queuing.

```cpp
long priority();
```

--------------------------------

### Example Bus Interface Class Declaration

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

This C++ code declares a custom bus interface class 'MyInterface' that inherits from 'StreamBusInterface'. It includes the necessary virtual methods to be implemented and a static creator method. The class is registered using 'RegisterStreamBusInterface'.

```cpp
#include <StreamBusInterface.h>

class MyInterface : StreamBusInterface
{
    // ... (internally used attributes and methods)

    MyInterface(Client* client);
    ~MyInterface();

    // StreamBusInterface virtual methods
    bool lockRequest(unsigned long lockTimeout_ms);
    bool unlock();
    bool writeRequest(const void* output, size_t size, unsigned long writeTimeout_ms);
    bool readRequest(unsigned long replyTimeout_ms, unsigned long readTimeout_ms, ssize_t expectedLength, bool async);
    bool supportsAsyncRead();
    bool supportsEvent();
    bool acceptEvent(unsigned long mask, unsigned long timeout_ms);
    bool connectRequest(unsigned long timeout_ms);
    bool disconnectRequest();
    void finish();

public:
    // creator method
    static StreamBusInterface* getBusInterface(
        Client* client, const char* busname,
        int addr, const char* param);
};

RegisterStreamBusInterface(MyInterface);

// ... (implementation)

```

--------------------------------

### Handle Mixed Data Types with @mismatch

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use the @mismatch exception handler and redirection to records when a device sends mixed data types. This example shows how to read a current value, handling both numeric and string responses.

```StreamDevice
read_current {
  out "CURRENT?"
  in "CURRENT %f A"
  @mismatch {
    in "%(\39c)"
  }
}
```

```StreamDevice
record (ai, "$(DEVICE):readcurrent") {
  field (DTYP, "stream")
  field (INP, "@$(DEVICETYPE).proto read_current($(DEVICE):message) $(BUS)")
}
record (stringin, "$(DEVICE):message") {
}
```

```StreamDevice
record (calcout, "$(DEVICE):clean_1") {
  field (INPA, "$(DEVICE):readcurrent.SEVR CP")
  field (CALC, "A#3")
  field (OOPT, "When Non-zero")
  field (OUT,  "$(DEVICE):clean_2.PROC")
}
record (stringout, "$(DEVICE):clean_2") {
  field (VAL, "OK")
  field (OUT,  "$(DEVICE):message PP")
}
```

--------------------------------

### Get Input Terminator

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Retrieves any terminator bytes that the bus interface should expect at the end of input.

```cpp
const char* getInTerminator(size_t& length);
```

--------------------------------

### Get Bus Interface Instance

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Static method to retrieve a bus interface instance for a given client and bus name. It checks if the interface class is responsible for the bus and if the address is valid. Returns a pointer to the interface on success, or NULL on failure.

```cpp
static StreamBusInterface* getBusInterface(Client* client, const char* busname, int addr, const char* param);
```

--------------------------------

### Output EGU field of the active record

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Outputs the EGU field of the currently active record. This is a simple example of I/O redirection.

```StreamDevice Format
out "%(EGU)s";
```

--------------------------------

### aao Record CHAR/UCHAR Input Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Inputs a string into the aao record when FTVL is CHAR or UCHAR. A maximum of NELM-1 characters can be read, and NORD is updated to the index of the first trailing zero.

```text
_Input:_ `VAL=_x_, NORD=length(_x_)`
```

--------------------------------

### Read Web Page Title with Regular Expressions

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Read the title of a web page by sending a GET request and using a regular expression to extract the content between the <title> tags. Ensure a sufficient reply timeout and handle potential case variations.

```StreamDevice
get_title {
  extrainput = ignore;
  replyTimeout = 1000;
  out "GET http://$1\r\n\r\n";
  in "%+.1/(?im)<title>(.*)<\/title>/";
}
```

```StreamDevice
record (stringin, "$(DEVICE):title") {
  field (DTYP, "stream")
  field (INP,  "@$(DEVICETYPE).proto get_title($(PAGE)) $(BUS)")
}
record (waveform, "$(DEVICE):longtitle") {
  field (DTYP, "stream")
  field (INP,  "@$(DEVICETYPE).proto get_title($(PAGE)) $(BUS)")
  field (FTVL, "CHAR")
  field (NELM, "100")
}
```

--------------------------------

### aao Record LONG or ENUM Input Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Inputs array elements as long integers, converting from the specified FTVL. The value is truncated if FTVL has a smaller data size than long.

```text
_Input:_ `VAL[i]=FTVL(_x[i])_`
```

--------------------------------

### Extracting HTML Title using Regex

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

This example demonstrates how to extract the content of an HTML title tag using a PCRE regular expression. It skips content before the opening tag and leaves content after the closing tag in the input buffer.

```StreamDevice
%/.1/<title>(.*)<\/title>/
```

--------------------------------

### aao Record DOUBLE Output Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Outputs array elements as doubles, applying the format converter. FTVL can be DOUBLE, FLOAT, INT64, UINT64, LONG, ULONG, SHORT, USHORT, CHAR, UCHAR, or ENUM.

```text
_Output:_ `_x[i]_=double(VAL[i])`
```

--------------------------------

### Quoted String Literals

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Examples of string literals using single and double quotes. Quotes of the other type can be used within the string. Long strings can be broken across lines by closing and reopening quotes.

```StreamDevice Protocol
"That's a string."
```

```StreamDevice Protocol
'Say "Hello"'
```

--------------------------------

### aao Record LONG or ENUM Output Example

Source: https://paulscherrerinstitute.github.io/StreamDevice/aao.html

Outputs array elements as long integers, applying the format converter. FTVL can be INT64, UINT64, LONG, ULONG, SHORT, USHORT, CHAR, UCHAR, or ENUM. Signed values are sign-extended, unsigned values are zero-extended.

```text
_Output:_ `_x[i]_=long(VAL[i])`
```

--------------------------------

### Request Write Output

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Initiates writing data to a device. Returns true if accepted, false otherwise. Does not block until completion.

```cpp
bool writeRequest(const void* output, size_t size, unsigned long writeTimeout_ms);
```

--------------------------------

### mbbiDirect Record: LONG Format - With Mask

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbbiDirect.html

For LONG format when MASK is not 0, output writes RVAL&MASK, and input reads _x_&MASK. MASK is initialized from NOBT.

```text
_Output:_ `_x_=RVAL&MASK`
_Input:_ `RVAL=_x_&MASK`
```

--------------------------------

### Initialize StreamDevice record with input/output link

Source: https://paulscherrerinstitute.github.io/StreamDevice/recordinterface.html

Initializes a record by passing its I/O link to StreamDevice for parsing and registering read/write functions. Typically calls streamInitRecord.

```c
static long initRecord(dbCommon *record)
{
    recordtypeRecord *rec = (recordtypeRecord *)record;

    return streamInitRecord(record, &rec->out, readData, writeData);
}

```

--------------------------------

### Basic Protocol Arguments for Motor Control

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Demonstrates how protocol arguments can differentiate similar protocols for motor axes X, Y, and Z.

```streamdevice
moveX { out "X GOTO %d"; }
moveY { out "Y GOTO %d"; }
moveZ { out "Z GOTO %d"; }
```

--------------------------------

### Input using protocol argument for record redirection

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Demonstrates using a protocol argument to specify a part of the record name for redirection. This is useful for avoiding full record names in protocol files.

```StreamDevice Format
in "%(\$1recordpart)f"
```

--------------------------------

### Download StreamDevice Repository

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Clones the StreamDevice Git repository to your local machine. This is the primary step for obtaining the source code.

```git
git clone https://github.com/paulscherrerinstitute/StreamDevice.git
```

--------------------------------

### Unified Protocol with Arguments

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Shows a single protocol definition using arguments to control different axes, reducing redundancy.

```streamdevice
move { out "$1 GOTO %d"; }
```

--------------------------------

### Add StreamDevice Dependencies to Makefile

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Include these lines in your application's Makefile to link against the StreamDevice, asyn, and pcre libraries.

```makefile
PROD_LIBS += stream
PROD_LIBS += asyn
PROD_LIBS += pcre

```

--------------------------------

### scalcout Record Initialization Fix

Source: https://paulscherrerinstitute.github.io/StreamDevice/scalcout.html

A required fix for the sCalcout.c file in versions up to synApps release 5.1 to ensure proper record initialization.

```c
        if(pscalcoutDSET->init_record ) {
            return (*pscalcoutDSET->init_record)(pcalc);
        }

```

--------------------------------

### Request Read Input

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Initiates reading input from a device. Returns true if accepted, false otherwise. Does not block until input is available.

```cpp
bool readRequest(unsigned long replyTimeout_ms, unsigned long readTimeout_ms, ssize_t expectedLength, bool async);
```

--------------------------------

### Include StreamDevice and Asyn DBDs in Application

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Add these lines to your application's xxxAppInclude.dbd file to enable StreamDevice and asyn support for serial, IP sockets, and VXI11.

```dbd
include "base.dbd"
include "stream.dbd"
include "asyn.dbd"
registrar(drvAsynIPPortRegisterCommands)
registrar(drvAsynSerialPortRegisterCommands)
registrar(vxi11RegisterCommands)

```

--------------------------------

### Configure Input Record for StreamDevice

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Use this snippet to create an input record (ai) that reads data using StreamDevice. Ensure the DTYP field is set to 'stream' and the INP field specifies the protocol file, protocol name, and bus.

```EPICS
record (ai, "PS1:I-get")
{
    field (DESC, "Read current of PS1")
    field (DTYP, "stream")
    field (INP,  "@ExamplePS.proto getCurrent PS1")
    field (EGU,  "A")
    field (PREC, "2")
    field (LOPR, "0")
    field (HOPR, "60")
    field (PINI, "YES")
    field (SCAN, "10 second")
}
```

--------------------------------

### Configure PCRE Include and Library Paths (Linux x86)

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Sets the include and library paths for the PCRE package on a Linux x86 system. This is necessary for enabling regular expression matching support in StreamDevice.

```makefile
PCRE_INCLUDE=/usr/include/pcre
PCRE_LIB=/usr/lib
```

--------------------------------

### Configure PCRE Include and Library Paths (Linux x86 64-bit)

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Specifies the include and library paths for the PCRE package on a 64-bit Linux system. This is required for regular expression support.

```makefile
PCRE_INCLUDE=/usr/include/pcre
PCRE_LIB=/usr/lib64
```

--------------------------------

### User Variables for Frequency Settings

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Illustrates the use of user variables to define shorthand for frequently used strings like 'FREQ' and format specifiers.

```streamdevice
f = "FREQ";     # sets f to "FREQ" (including the quotes)
f1 = $f " %f";  # sets f1 to "FREQ %f"
```

--------------------------------

### mbboDirect Record: MASK Initialization

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbboDirect.html

Explains how the MASK field is initialized based on NOBT and SHFT values. The record then calculates RVAL based on the VAL field shifted.

```text
`MASK` is initialized to `NOBT` 1-bits shifted left by `SHFT` (`((2^NOBT)-1)<<SHFT`). The record calculates `RVAL=VAL<<SHFT`.
```

--------------------------------

### Protocol Using User Variables for Frequency

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Demonstrates 'getFrequency' and 'setFrequency' protocols that utilize user-defined variables for cleaner syntax.

```streamdevice
getFrequency {
    out $f "?"; # same as: out "FREQ?"; 
    in $f1;     # same as: in "FREQ %f"; 
}

setFrequency {
    out $f1;    # same as: out "FREQ %f"; 
}
```

--------------------------------

### mbbiDirect Record: LONG Format - No Mask

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbbiDirect.html

For LONG format when MASK is 0 (NOBT not set), output writes the value to VAL, and input reads from VAL.

```text
_Output:_ `_x_=VAL`
_Input:_ `VAL=_x_`
```

--------------------------------

### Set Variable Syntax

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Use this syntax to set a variable in a protocol file. Variables can be system or user-defined.

```protocol
_variable_ = _value_;
```

--------------------------------

### Configure Output Record for StreamDevice

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Use this snippet to create an output record (ao) that writes data using StreamDevice. Set the DTYP field to 'stream' and the OUT field to specify the protocol file, protocol name, and bus.

```EPICS
record (ao, "PS1:I-set")
{
    field (DESC, "Set current of PS1")
    field (DTYP, "stream")
    field (OUT,  "@ExamplePS.proto setCurrent PS1")
    field (EGU,  "A")
    field (PREC, "2")
    field (DRVL, "0")
    field (DRVH, "60")
    field (LOPR, "0")
    field (HOPR, "60")
}
```

--------------------------------

### Configure Serial Port with Software Flow Control

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Configures the serial port to use software flow control (XON/XOFF) by setting 'ixon' and 'ixany' options to 'Y'.

```shell
asynSetOption ("PS1", 0, "ixon", "Y")
asynSetOption ("PS1", 0, "ixany", "Y")

```

--------------------------------

### Write Values from Other Records using Redirection

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use redirection to records to write values from other records on the same IOC. Specify record names or record.FIELD directly after the '%' or use protocol arguments like '$1'.

```Device Support
acquire {out 'ACQUIRE "%(\1:directory)s/%s",%(\1:time).3f;';}
record (stringout, "$(DEVICE):getimage") {
  field (DTYP, "stream")
  field (OUT, "@$(DEVICETYPE).proto acquire($(DEVICE)) $(BUS)")
}
```

--------------------------------

### Connection Callback

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Callback function to be called when the device has connected. Can be called asynchronously. Defaults to StreamIoSuccess.

```cpp
void connectCallback(IoStatus status = StreamIoSuccess);
```

--------------------------------

### Using Protocol Arguments

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Reference arguments passed to a protocol using $1, $2, etc. Arguments can be referenced directly or within strings by escaping them with a backslash.

```text
field (OUT, "@protocolfile protocol(arg1,arg2,arg3) bus")
In the protocol, reference arguments as $1 $2 $3 or inside strings as "\$1 \$2 \$3".
```

--------------------------------

### StreamBusInterface Constructor

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Constructor for the StreamBusInterface. It should pass the client pointer to the base class constructor.

```cpp
StreamBusInterface(Client* client);
```

--------------------------------

### Request Connection

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Requests a connection to the device with a specified timeout. Should not block but return immediately. Calls connectCallback upon successful connection or if connection fails within the timeout.

```cpp
bool connectRequest(unsigned long timeout_ms);
```

--------------------------------

### Binary Converter with Default Characters

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Equivalent to %b, this format uses '0' and '1' to represent binary digits.

```StreamDevice Format
%B01
```

--------------------------------

### Read Callback

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Called when input has been received. Returns the number of bytes expected or a negative value for unspecified amounts.

```cpp
ssize_t readCallback(IoStatus status, const void* buffer = NULL, size_t size = 0);
```

--------------------------------

### Print String Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for printing a null-terminated string to a stream buffer.

```C++
bool printString(const StreamFormat& fmt, StreamBuffer& output, const char* value);
```

--------------------------------

### System Variable: MaxInput

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Sets the maximum number of bytes to read before terminating input, used for devices without terminators. '0' means infinite.

```protocol
MaxInput = 0;
```

--------------------------------

### Raw Converter for Unsigned Input with Width

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Reads bytes into an unsigned integer value. '%02r' reads 2 bytes and treats the value as unsigned.

```StreamDevice Format
in "%02r";
```

--------------------------------

### Move Postfix Sign to Front

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Moves a postfix sign (like '+' or '-') to the front of a number. This is useful for standardizing the representation of signed numbers.

```streamdevice
%#/([^+-])*([+-])/\2\1/
```

--------------------------------

### Check Event Support

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Implement this method to indicate if the bus interface supports event notifications. The default implementation returns false.

```cpp
bool supportsEvent();
```

--------------------------------

### Compare input with formatted current value

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Compares the input against the current value formatted as a float with 3 decimal places. The format succeeds only if the input matches.

```StreamDevice
in "%=.3f";
```

--------------------------------

### Configure Debug and Error Messages (iocsh)

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Sets various variables using iocsh commands to control debug and error message behavior. Enables debug and error messages, colored output, sets a dead time for repeated errors, enables timestamps, and redirects debug output to a log file.

```shell
var streamError 1
var streamDebug 1
var streamDebugColored 1
var streamErrorDeadTime 30
var streamMsgTimeStamped 1
streamSetLogfile("logfile.txt")

```

--------------------------------

### System Variable: LockTimeout

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Configures the milliseconds to wait for exclusive device access before timing out. Affects the first 'out' command.

```protocol
LockTimeout = 5000;
```

--------------------------------

### Configure PCRE Top Directory

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Defines the top-level directory for the PCRE package in the StreamDevice `RELEASE` file. This is used when PCRE is built as an EPICS module.

```makefile
PCRE=/home/epics/pcre
```

--------------------------------

### Print Pseudo Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for printing a pseudo-value to a stream buffer.

```C++
bool printPseudo(const StreamFormat& fmt, StreamBuffer& output);
```

--------------------------------

### Read decimal number followed by a percent sign

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Reads a decimal number and then expects a literal '%' character immediately following it.

```StreamDevice
in "%d%%";
```

--------------------------------

### System Variable: ReplyTimeout

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Defines the milliseconds to wait for the first input byte from the device. Affects 'in' commands.

```protocol
ReplyTimeout = 1000;
```

--------------------------------

### System Variable: WriteTimeout

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Sets the milliseconds to wait for output to be written after acquiring device access. Affects 'out' commands.

```protocol
WriteTimeout = 100;
```

--------------------------------

### Finish Protocol

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Cleans up resources and cancels outstanding requests for a client after a protocol ends.

```cpp
void finish();
```

--------------------------------

### System Variable: ExtraInput

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Determines how to handle extra input bytes after parsing is complete. Can be 'Error' or 'Ignore'. Affects 'in' commands.

```protocol
ExtraInput = Error;
```

--------------------------------

### Escape Sequences in Strings

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Demonstrates various escape sequences available within quoted string literals for special characters and byte representations.

```StreamDevice Protocol
"\"\\'\%\\"
```

```StreamDevice Protocol
"\a\b\t\n\r\e"
```

```StreamDevice Protocol
"\x41\010\1"
```

```StreamDevice Protocol
"?"
```

```StreamDevice Protocol
"\_"
```

```StreamDevice Protocol
"\$variable_name"
```

--------------------------------

### Write Multiple Numeric Values using Calcout Record

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use a calcout record and redirection to fields to write up to 12 numeric values. Ensure a valid expression is specified in the CALC field, even if unused.

```Device Support
write_ABC {out "A=%(A).2f B=%(B).6f C=%(C).0f";}
record (calcout, "$(RECORD)") {
  field (INPA, "$(A_RECORD)")
  field (INPB, "$(B_RECORD)")
  field (INPC, "$(C_RECORD)")
  field (CALC, "0")
  field (DTYP, "stream")
  field (OUT, "@$(DEVICETYPE).proto write_ABC $(BUS)")
}
```

--------------------------------

### scalcout Record STRING Input Format

Source: https://paulscherrerinstitute.github.io/StreamDevice/scalcout.html

Defines the input format for STRING type values in scalcout records. SVAL is used to read the string value.

```text
SVAL=_x_
```

--------------------------------

### scalcout Record STRING Output Format

Source: https://paulscherrerinstitute.github.io/StreamDevice/scalcout.html

Defines the output format for STRING type values in scalcout records. OSV is used for the string value.

```text
_x_=OSV
```

--------------------------------

### Scan String Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for scanning a string from an input buffer, with size management.

```C++
ssize_t scanString(const StreamFormat& fmt, const char* input, char* value, size_t& size);
```

--------------------------------

### Binary Converter with Custom Characters and Little-Endian

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Prints or scans an unsigned integer using custom characters for zero and one, with the '#' flag reversing bit order to little-endian.

```StreamDevice Format
%B.! or %B\x00\xff
```

--------------------------------

### mbboDirect Record: LONG/ENUM Input (MASK=0)

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbboDirect.html

For LONG or ENUM formats when MASK is 0 (NOBT not set), this defines the input behavior. RAL is set to x, and VAL is derived from RVAL shifted.

```text
_Input:_ `RAL=_x_`,`VAL=RVAL>>SHFT`
```

--------------------------------

### mbboDirect Record: LONG/ENUM Output (MASK=0)

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbboDirect.html

For LONG or ENUM formats when MASK is 0 (NOBT not set), this defines the output behavior. RVAL is set to the value of x.

```text
_Output:_ `_x_=RVAL`
```

--------------------------------

### Byte Value Representations

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Shows how to represent bytes using decimal, hexadecimal, or octal numbers. ASCII symbolic names can also be used for specific byte codes.

```StreamDevice Protocol
72 101 108 108 111 32 119 111 114 108 100 13 10
```

```StreamDevice Protocol
NUL SOH STX ETX EOT ENQ ACK BEL BS HT LF VT FF CR SO SI DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EM SUB ESC FS GS RS US DEL
```

--------------------------------

### EPICS Base Fix for Windows

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

A required fix for EPICS base versions R3.14.8.2 and earlier on Windows to build StreamDevice. Add this line to `src/iocsh/iocsh.h`.

```c
epicsShareFunc int epicsShareAPI iocshCmd(const char *command);
```

--------------------------------

### Implement readData for StreamDevice records

Source: https://paulscherrerinstitute.github.io/StreamDevice/recordinterface.html

Handles reading data based on format type, including emulation of record conversion and monitor updates. Use when processing input links for records.

```c
static long readData(dbCommon *record, format_t *format)
{
    recordtypeRecord *rec = (recordtypeRecord *)record;
    unsigned long rval;
    unsigned short monitor_mask;

    switch (format->type)
    {
        case DBF_ULONG:
        case DBF_LONG:
        case DBF_ENUM:
            if (streamScanf(record, format, &rval) == ERROR) return ERROR;
            rec->rval = rval;
            if (record->pact) return OK;
            /* emulate convertion to val */
            rec->val = rval * rec->eslo + rec->eoff;
            break;
        case DBF_DOUBLE:
            if (streamScanf(record, format, &rec->val) == ERROR) return ERROR;
            break;
            if (record->pact) return DO_NOT_CONVERT;
        default:
            return ERROR;
    }
    /* In @init handler, no processing, enforce monitor updates. */
    monitor_mask = recGblResetAlarms(record);
    if (rec->oraw != rec->rval)
    {
        db_post_events(record, &rec->rval, monitor_mask | DBE_VALUE | DBE_LOG);
        rec->oraw = rec->rval;
    }
    if (!(fabs(rec->mlst - rec->val) <= rec->mdel))
    {
        monitor_mask |= DBE_VALUE;
        ao->mlst = rec->val;
    }
    if (!(fabs(rec->alst - rec->val) <= rec->adel))
    {
        monitor_mask |= DBE_VALUE;
        ao->alst = rec->val;
    }
    if (monitor_mask)
        db_post_events(record, &rec->val, monitor_mask);
    return OK;
}

```

--------------------------------

### Accept Event with Mask and Timeout

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Call this method to wait for a specific event within a given timeout. The mask defines the event type, and the callback is invoked upon event arrival or timeout. This call must not block.

```cpp
bool acceptEvent(unsigned long mask, unsigned long timeout_ms);
```

--------------------------------

### Storing Values in Other Records via Redirection

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use redirection to store values in other records on the same IOC, avoiding record names in protocol files by using protocol arguments. The PP attribute on Record B's VAL field automatically processes Record B.

```StreamDevice Protocol
read_AB {out "GET A,B"; in "A=%f, B=%(\$\(1\))f";}
```

```EPICS Record Definition
record (ai, "$(DEVICE):A") {
  field (DTYP, "stream")
  field (INP, "@$(DEVICETYPE).proto read_AB($(DEVICE):B) $(BUS)")
  field (SCAN, "1 second")
}
record (ai, "$(DEVICE):B") {
}
```

--------------------------------

### Write float with specific formatting

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Writes the value of the 'HOPR' field as a floating-point number, formatted to 7 characters wide with a precision of 4 decimal places.

```StreamDevice
out "%(HOPR)7.4f";
```

--------------------------------

### Registering a Converter Class

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Registers a converter class for specified conversion characters. This macro should be called once per class in the global file context.

```C++
RegisterConverter(_converterClass_, "_characters_");
```

--------------------------------

### System Variable: Separator

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Defines the string used as a separator when formatting or parsing array values. Affects 'out' and 'in' commands.

```protocol
Separator = "";
```

--------------------------------

### Write zero-padded hexadecimal integer

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Writes an integer in hexadecimal format, padded with leading zeros to a width of 10 characters. The '#' flag ensures the '0x' prefix is included.

```StreamDevice
out "%#010x";
```

--------------------------------

### Print Double Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for printing a double-precision floating-point value to a stream buffer.

```C++
bool printDouble(const StreamFormat& fmt, StreamBuffer& output, double value);
```

--------------------------------

### StreamDevice Device Support Structure Definition

Source: https://paulscherrerinstitute.github.io/StreamDevice/recordinterface.html

Defines the structure for device support in StreamDevice, including standard functions and their assignments. This structure is exported using epicsExportAddress.

```c
struct {
    long number;
    DEVSUPFUN report;
    DEVSUPFUN init;
    DEVSUPFUN init_record;
    DEVSUPFUN get_ioint_info;
    DEVSUPFUN write;
} devrecordtypeStream = {
    5,
    streamReport,
    streamInit,
    initRecord,
    streamGetIointInfo,
    streamWrite
};

epicsExportAddress(dset,devrecordtypeStream);

```

--------------------------------

### Scan Pseudo Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for scanning a pseudo-value from an input buffer, managing cursor position.

```C++
ssize_t scanPseudo(const StreamFormat& fmt, StreamBuffer& inputLine, size_t& cursor);
```

--------------------------------

### Implement writeData Function for Record Interface

Source: https://paulscherrerinstitute.github.io/StreamDevice/recordinterface.html

This function is called to handle printing format converters or input records with the '=' flag. It casts the dbCommon pointer to the specific record type and uses a switch statement based on format->type to access and print appropriate record fields (e.g., .VAL for DBF_DOUBLE, .RVAL for DBF_LONG/DBF_ULONG/DBF_ENUM) using streamPrintf. It returns ERROR for unsupported types.

```c
static long writeData(dbCommon *record, format_t *format)
{
    recordtypeRecord *rec = (recordtypeRecord *)record;

    switch (format->type)
    {
        case DBF_ULONG:
        case DBF_ENUM:
            return streamPrintf(record, format, (unsigned long)rec->rval);
        case DBF_LONG:
            return streamPrintf(record, format, (long)rec->rval);
        case DBF_DOUBLE:
            return streamPrintf(record, format, rec->val);
        default:
            return ERROR;
    }
}

```

--------------------------------

### Read decimal number with default on failure

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Attempts to read a decimal number. If the conversion fails, it defaults to a value of 0.

```StreamDevice
in "%?d";
```

--------------------------------

### Write Array Values with Same Type and Separator

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use array records (e.g., waveform, aao) when all values have the same type and are separated by the same string. The format specifier is repeated for each element.

```Device Support
array_out {separator=", "; out "an array: (%.2f)";}
```

--------------------------------

### Raw Converter with Precision and Little-Endian

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Reads or writes a signed/unsigned integer in its raw byte representation. '%.2r' specifies writing the 2 least significant bytes.

```StreamDevice Format
out "%.2r";
```

--------------------------------

### mbboDirect Record: LONG/ENUM Output (MASK!=0)

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbboDirect.html

For LONG or ENUM formats when MASK is not 0, this defines the output behavior. RVAL is masked with MASK before being assigned to x.

```text
_Output:_ `_x_=RVAL&MASK`
```

--------------------------------

### Write Callback

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Called after output transmission is complete, or if a timeout or fault occurs.

```cpp
void writeCallback(IoStatus status = StreamIoSuccess);
```

--------------------------------

### mbboDirect Record: LONG/ENUM Input (MASK!=0)

Source: https://paulscherrerinstitute.github.io/StreamDevice/mbboDirect.html

For LONG or ENUM formats when MASK is not 0, this defines the input behavior. RBV and RVAL are set based on x and MASK, and VAL is derived from RVAL shifted.

```text
_Input:_ `RBV=RVAL=_x_&MASK`,`VAL=RVAL>>SHFT`
```

--------------------------------

### Register Stream Bus Interface

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Registers a bus interface class. This macro must be called exactly once for each bus interface class in the global file context during initialization.

```cpp
RegisterStreamBusInterface(_interfaceClass_);
```

--------------------------------

### Expect exactly 5 decimal digits

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Reads exactly 5 decimal digits. If fewer digits are present, the format fails, indicating data loss.

```StreamDevice
in "%!5d";
```

--------------------------------

### Configure Debug and Error Messages (vxWorks)

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Sets various shell variables to control debug and error message behavior in a vxWorks environment. Enables debug and error messages, colored output, sets a dead time for repeated errors, enables timestamps, and redirects debug output to a log file.

```shell
streamError=1
streamDebug=1
streamDebugColored=1
streamErrorDeadTime=30
streamMsgTimeStamped=1
streamSetLogfile("logfile.txt")

```

--------------------------------

### Read Number from Web Page with Regular Expressions

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Extract a specific number from a web page by matching known preceding text and then capturing the numeric value. This method is suitable for predictable data formats and requires careful regex construction to avoid errors.

```StreamDevice
get_title {
  extrainput = ignore;
  replyTimeout = 1000;
  out "GET http://$1\r\n\r\n";
  in "%*/Interesting value:/%f more text";
}
```

--------------------------------

### Replace String with Substitution and Limit Matches

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Replaces a specified string with a substitution, limiting the number of replacements and processing only the last N characters. Useful for cleaning or formatting specific parts of data.

```streamdevice
%#+-10.2/ab/X/
```

--------------------------------

### Request Bus Lock

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Requests exclusive access to a device. Returns true if accepted, false otherwise. Adds to a queue if the device is already locked.

```cpp
bool lockRequest(unsigned long timeout_ms);
```

--------------------------------

### Read a string of alphanumeric characters and underscores

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Reads a sequence of characters that are alphanumeric or underscores into a string.

```StreamDevice
in "%[_a-zA-Z0-9]";
```

--------------------------------

### System Variable: Terminator

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Defines the string appended to output and used to identify input termination. Affects 'out' and 'in' commands.

```protocol
Terminator
```

--------------------------------

### Scan Double Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for scanning a double-precision floating-point value from an input buffer.

```C++
ssize_t scanDouble(const StreamFormat& fmt, const char* input, double& value);
```

--------------------------------

### scalcout Record DOUBLE Input Format

Source: https://paulscherrerinstitute.github.io/StreamDevice/scalcout.html

Defines the input format for DOUBLE type values in scalcout records.

```text
VAL=_x_
```

--------------------------------

### Process Unsolicited Data with I/O Intr

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Use 'I/O Intr' processing to handle unsolicited input. The record receives any input and processes it only when the input matches the specified pattern.

```Device Support
read {
in "new value = %f";
}
record (ai, "$(RECORD)") {
  field (DTYP, "stream")
  field (INP, "@$(DEVICETYPE).proto read $(BUS)")
  field (SCAN, "I/O Intr")
}
```

--------------------------------

### Input float to other record's VAL field

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Stores a received floating-point value in the VAL field of another record, then processes that record. The target record should use `DTYP="Soft Channel"`.

```StreamDevice Format
in "%(otherrecord)f";
```

--------------------------------

### Release Bus Interface

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Releases the bus interface instance. The default implementation calls delete, which may need to be overridden if the interface was not allocated with 'new'.

```cpp
void release();
```

--------------------------------

### Convert Previous Characters to Uppercase

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Converts the previous N characters to uppercase. This is useful for standardizing case in specific data fields.

```streamdevice
%#-2/.*/\U0/
```

--------------------------------

### Print Long Method Signature

Source: https://paulscherrerinstitute.github.io/StreamDevice/formatconverter.html

Signature for printing a long integer value to a stream buffer.

```C++
bool printLong(const StreamFormat& fmt, StreamBuffer& output, long value);
```

--------------------------------

### Configure Serial Port with Hardware Flow Control

Source: https://paulscherrerinstitute.github.io/StreamDevice/setup.html

Modifies the serial port configuration to enable hardware flow control by setting 'clocal' to 'N' and 'crtscts' to 'Y'.

```shell
asynSetOption ("PS1", 0, "clocal", "N")
asynSetOption ("PS1", 0, "crtscts", "Y")

```

--------------------------------

### Request Disconnection

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Requests an explicit disconnection from the device. Should return immediately. Calls connectCallback once the bus is disconnected.

```cpp
bool disconnectRequest();
```

--------------------------------

### Disconnection Callback

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Callback function to be called when the device has disconnected. Can be called asynchronously. Defaults to StreamIoSuccess.

```cpp
void disconnectCallback(IoStatus status = StreamIoSuccess);
```

--------------------------------

### aai Record CHAR/UCHAR Output Format as String

Source: https://paulscherrerinstitute.github.io/StreamDevice/aai.html

Treats the complete aai as a single string for output when FTVL is CHAR or UCHAR. Prints the first NORD characters.

```text
If `FTVL=="CHAR"` or `FTVL="UCHAR"`:
     _Output:_ `_x_=range(VAL,0,NORD)`  
The first`NORD` characters are printed, which might be less than `NELM`.
```

--------------------------------

### Input integer to other record's RVAL field

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Stores a received integer value in the RVAL field of another record, then processes that record. The target record should use `DTYP="Raw Soft Channel"` for proper conversion.

```StreamDevice Format
in "%(otherrecord.RVAL)i";
```

--------------------------------

### System Variable: ReadTimeout

Source: https://paulscherrerinstitute.github.io/StreamDevice/protocol.html

Specifies the milliseconds to wait for more input bytes after the device stops sending. Affects 'in' commands.

```protocol
ReadTimeout = 100;
```

--------------------------------

### Supports Asynchronous Read

Source: https://paulscherrerinstitute.github.io/StreamDevice/businterface.html

Checks if the bus interface supports asynchronous read operations.

```cpp
bool supportsAsyncRead();
```

--------------------------------

### AI Record Configuration for ROI End with I/O Intr

Source: https://paulscherrerinstitute.github.io/StreamDevice/processing.html

Configures an AI record to process the end value of a Region of Interest (ROI) from a device using I/O Intr mode. This allows the record to update automatically when the device sends ROI data, even without a direct request.

```EPICS
record (ai "ROI:end") {
    field (DTYP, "stream")
    field (INP,  "@myDev.proto getROIend dev1")
    field (SCAN, "I/O Intr")
}
```

--------------------------------

### Filtering and Skipping Values with I/O Intr

Source: https://paulscherrerinstitute.github.io/StreamDevice/tipsandtricks.html

Utilize I/O Intr processing and the value skipping operator ('%*') to filter and read specific values from messages. Record B uses I/O Intr to process inputs not matched by Record A.

```StreamDevice Protocol
read_A {out "GET A,B"; in "A=%f, B=%*f";}
read_B {in "A=%*f, B=%f";}
```

```EPICS Record Definition
record (ai, "$(DEVICE):A") {
  field (DTYP, "stream")
  field (INP, "@$(DEVICETYPE).proto read_A $(BUS)")
  field (SCAN, "1 second")
}
record (ai, "$(DEVICE):B") {
  field (DTYP, "stream")
  field (INP, "@$(DEVICETYPE).proto read_B $(BUS)")
  field (SCAN, "I/O Intr")
}
```

--------------------------------

### Read a float value

Source: https://paulscherrerinstitute.github.io/StreamDevice/formats.html

Reads a single floating-point value from the input stream.

```StreamDevice
in "%f";
```
Tokens:
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